[asterisk-users] VOIP Bandwidth questions

[Erick Perez]

This one will surely heat up.

Usually the telcos have to calculate the subscribers vs telco capacity.
I use simple figures, so extrapolate this to millions of customers,
millions of lines, peak amount of calls at any given time of the day
and of course houndreds,thousands of millions of dollars in equipment.

For example:
Telco A has 100 subscribers to his phone service in a city (home and
business), so he needs to ask himself
a- Will the telco buy a switch that can handle 100 calls
simultaneously? So he can provide service to his subscribers 100% of
the time at any time of the day even during riots,panic,flood,etc?
b- Or will the telco go for a balance and guess that at the peak time
of the day he will have 75 simultaneous call, so he goes out and buy a
switch that handles 75-80 calls at the same time?
c- how many trunks will the Telco have to talk to other telcos? So
telco in City A can communicate with Telco in city B (or even in the
same city)?

International voice providers suffer from this kind of problem. Some
sell plastic cards with a local phone number and a pin so you call
them to call to other cities/countries but that cheap voice provider
has, let's say, ten thousand long distance lines and ten thousand
local phone numbers, but they sell 100k plastic cards a month with a
peak usage 3 times every ten days of 12thousand lines? obviously 2
thousand callers wont get connected (only 3 times every ten days in a
specific time range) but the other 7 days the peak usage is 10thousand
calls?
Every ten days the provider try to connect 106k calls but fail to
connect 6k calls, that's 6% failure rate every ten days (100% in a 7
days period and 98% in those 3 days). Can you live with that failure
ratio? that's up to you.

I don't work for a Telco, but a Telco may apply the dialup-internet
rule (and they live happy with it) for 30subscribers-to-1line home
users and 10(or 5)subscribers-to-1line for business. (correct me if
I'm wrong please it will be nice to know real figures).

So apply the same rule to you VoIP hosting.
-What codec will you use? let say g711 and let's say it uses
100kilobits per leg.
-How many subscribers will you have in a 6 month period? 500
-So to provide all of them with service you will need 48Megabits of
bandwith all the time just to connect to your Telco equipments.
- But you decide that you analyzed the usage patterns of your service
and you will have only 125 subscribers calling other 125 subscribers
(this is called On-Net) at peak time every day at 6pm (rush hour). So,
go out and buy 24mbits of bandwidth only.
- But you suddenly have the option to hire "burst IP service" where
your IP carrier can provide you with more bandwidth if your usage
starts to rise in any given time of the day. So you calculate again
that your minimum constant usage at any time of the day is 40 users
On-Net, so go out and buy 5mbits (for a total of 50 calls) of
bandwidth with burst IP enabled from 6pm to 8pm of 48mbits (or
24mbits).
This scenario is only subscriber----your_company----subscriber.
you also need to calculate subscriber--your_company----other_telcos

And the last but most important question is: how much money do you
have to burn on this?
100% Uptime full-service, Top Carrier Class performance (and even they
get busy sometimes)?
or almost perfect service with the once-in-awhile glitch of "we're
sorry all circuits are busy, please try again".


Hope this helps,

How many times (at least in my country) haven't you suffered from "Im
sorry all circuits are busy, please try again" during christmas
midnight, new years eve, election days or similar behaviors that cause
massive amounts of calls being initiated and received?

So the answer to your question

On 11/2/06, mail-lists <mail-lists at peachnet.com> wrote:
> Hello everyone,
>
> This probably isn't the correct place to ask this but I thought I'd
> check here first.
>
> We're getting ready to roll out a hosted pbx solution on  a very limited
> trial basis (some company employees are going to get voip service at
> home). Our main issue is of course bandwidth. We have enough bandwidth
> (spread across two locations) to accommodate the few employees (around
> 10) for the near future but we're worried about how this is going to
> scale. Obviously at some point we'll need to consider 'real' bandwidth.
>
> My question is this: How do huge voip companies like vonage handle
> bandwidth. I'm pretty sure that they have to have sufficient bandwidth
> available for X numbers of simultaneous calls, in other words ALL VOIP
> traffic runs through their servers, right? My boss is of the mind that
> there is no way that this is a viable business model and his insistence
> has me doubting myself.
>
> So, to clarify - Vonage has to have the necessary bandwidth to handle
> whatever amount of simultaneous calls. I can imagine that one vonage
> user calling another vonage user would use some sort of sip re-invite
> and perhaps even calls to other huge providers (packet8) are direct
> client to client. (Last time I read about this it seems that even calls
> to other large voip providers go through the PSTN  though). Barring voip
> to voip calls, everything must run through their bandwidth right?
>
> If I'm right on this, I guess we need to come up with some sort of
> viable business model to do sell our own service. I want to concentrate
> on smb clients to whom we can then provide an asterisk box which would
> leave our bandwidth free, but my boss isn't particularly keen on this
> route.
>
>
> Anyways,
>
> Thanks for any insight and advice on this question, sorry if I'm asking
> this in the wrong place
>
>
> Thanks,
>
> Steve
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-- 
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Erick Perez
Panama Sistemas
Integradores de Telefonia IP y Soluciones Para Centros de Datos
Panama, Republica de Panama
Cel Panama. +(507) 6694-4780
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